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Slide Rules

Index by Makers & Retailers

Hundreds of companies around the world were involved in the production of slide rules from the 18th to the 20th centuries. Click on one of the names below to see the objects in this collection that were associated with that firm.

The Frederick Post Company, a 20th-century manufacturer and retailer of scientific instruments based in Chicago, did not make its own slide rules. From 1932, its exclusive supplier of linear slide rules was Hemmi, a Japanese firm. Hemmi was known for using a large-diameter variety of bamboo grown in Kagoshima Prefecture on the island of Kyushu. Company founder Jiro Hemmi (1878–1953) patented this innovation in several nations, including the United States in 1920.

While Post usually sold standard Hemmi models, around 1951 Hemmi created two ten-inch slide rules solely for Post, which sold in the United States as the model 1450 Versatrig and model 1460 Versalog. The Versalog was especially popular, selling several hundred thousand copies.

This example is bamboo, coated on all sides (except the ends) with white celluloid. The rule is held together with metal posts, one of which is engraved on the front: Wm. Krutz. The glass indicator has a metal frame with plastic sides. One side is marked: HEMMI JAPAN. The other side bears a Post logo in red, which has largely been rubbed away. The red Post logo and the serial number 015836 appear on the right front of the slide. The serial number indicates the rule was manufactured in 1959. This is confirmed by the date code JI on the bottom edge of the rule, which corresponds to a manufacturing date of September 1959.

The top edge of the rule is marked: CAT. NO. 1460; VERSALOG; FREDERICK POST CO.; HEMMI BAMBOO – JAPAN. The front of the base has LL0, LL/0, K, DF, D, R1, R2, AND L scales. The front of the slide bears CF, CIF, CI, and C scales. The LL/0, CIF, and CI scales are numbered in red. The back of the base has LL/1, LL/2, LL/3, D, LL3, LL2, AND LL1 scales. The back of the slide has T, Sec T and ST, Cos and S, and C scales. The LL/1, LL/2, LL/3, T, and Sec T scales are numbered in red. All the other scales are navy.

The rule fits into a black Fabrikoid case with a leather flap (stamped POST). The case could be hung from the user's belt, and it is labeled: W. K. KRUTZ. The case is stored in a red, white, and black cardboard box, along with a guarantee from Post and a ruler-sized white plastic set of conversion tables, copyrighted in 1950 by the Eugene Dietzgen Co., another prominent slide rule manufacturer. The rule also arrived with an instruction booklet, 1978.0800.02.

This yellow aluminum circular slide rule has three clear plastic indicators, one blank. The other indicator on the front is marked in red to denote the C, CI, A, AF, L, FA, LL2, LL1, DS, DT, and M scales. The indicator on the back is marked in red to denote the C, S,ST, and T scales. A ring of numbers under the scales on the back permits conversions from fractions to decimals.

The center of the front is marked: CIRCULAR SLIDE RULE – dial rule (/) PICKETT. The center of the back is marked: dial rule (/) NO 101-C. A triangular Pickett logo, of the form used between 1950 and 1958, appears at the bottom of the center; CHICAGO is printed below the logo.

Pickett & Eckel, a slide rule manufacturer based in Chicago and Alhambra, Calif., distributed a small booklet with this instrument, one of the few circular slide rules sold by the company and possibly the only circular model it manufactured. Maurice L. Hartung, a University of Chicago mathematics professor associated with the company, wrote the instruction manual (1981.0922.13). The booklet is copyrighted 1957, and the logo on this copy was used by the company between 1958 and 1962. Thus, this slide rule dates to about 1958.

This ten-inch mahogany duplex slide rule is faced with yellowed white celluloid and held together with corroded L-shaped end pieces. On one side, the base has A and D scales, with B, S, and C scales on the slide. The left end of the slide is marked in red: < 4092 >. The bottom of the base is marked in red: KEUFFEL & ESSER CO. N.Y.; PAT. JUNE 5. '00 DEC. 22. '08. On the other side, the base has LL1, LL2, LL3, D, and L scales, with C, T, and CI scales on the base. The indicator is frameless glass with plastic edges fastened with screws. One edge is marked: K&E.CO.N.Y. (/) PAT.8.17.15.

Keuffel & Esser of New York offered model 4092 from about 1909 to 1921. The frameless glass indicator was introduced in 1915. The rule sold for $8.00 from 1909 through 1915 and for $12.50 in 1921. This example fits in a cardboard case covered with black leather and marked: KEUFFEL & ESSER Co. (/) LOG. LOG. (/) SLIDE RULE. For instructions, see 1981.0993.02. Later examples of K&E Log Log slide rules in the collections include 1984.1068.02, MA*318479, 1990.0687.01, 1986.0790.03, and 1987.0085.01.

The donor, William J. Ellenberger (1908–2008), studied electrical and mechanical engineering at The George Washington University between 1925 and 1934. He then worked for the Potomac Electric Power Company and the National Bureau of Standards. During World War II, he served in the U.S. Army Signal Corps. He was a civilian construction management engineer for the army from 1954 to 1968, when he became a private consultant.

This is a two-foot, two-fold boxwood rule with a brass hinge and endpieces. Half of one side is a slide rule with A and D scales on the base and B and C scales on the slide. As with MA*306697.01, the C scale is the same as the A and B scales (the square of the D scale), instead of the same as the D scale, as on modern Mannheim slide rules. Below the D scale is marked: SQUARE CYLINDER GLOBE (3 times) ROUTLEDGE'S ENGINEER.

The first three marks form headings for the tables on the other half of this side when the instrument is folded. The tables give conversion factors from the volumes of geometric solids to units of volume, in both the "old" and imperial systems; conversion factors from the volumes of geometric solids to the weights in pounds of various substances; the areas of polygons from 5 to 12 sides; the gauge points of a circle; and gauge points for pumping engines, to find the diameters of steam cylinders that will work pumps of specified diameter at 7 pounds per square inch.

The other side has a scale of 24 inches along one edge, divided to sixteenths of an inch for 9 inches and to eighths of an inch for the rest of the scale. There are also scales for making scale drawings that are 1, 3/4, 1/2, and 1/4 inches to the foot. This side is marked: T. ASTON THE ORIGINAL MAKER WARRANTED. One outside edge has scales for 10 and 12 parts to the inch; the other outside edge divides one foot into 100 parts.

This form of slide rule was invented by Joshua Routledge, a seller of iron goods, in 1808 or 1809. He discussed it in the 1813 (4th) edition of Instructions for the Engineer's Improved Sliding Rule. According to Gloria Clifton, there were two rule makers named Thomas Aston, presumably a father and son, who were in business at various addresses in Birmingham, England, from 1818 to 1862. The references to pre-imperial system units of measure suggest the rule might have been made shortly after the imperial system was adopted in 1824. This instrument was found in the home of Grace Speer, granddaughter of Alfred Speer (1823–1910), an inventor and wine merchant in Passaic, N.J.

The top edge of the rule is marked: PATS. PEND. MADE IN U.S.A. 4081-5 LOG LOG DUPLEX DECITRIG ® COPYRIGHT 1947 BY KEUFFEL & ESSER CO. PATS. 2,500,460 2,168,056 2,170,144 2,285,722 2,422,649. These patents were issued between 1939 and 1950. They dealt with the arrangement of scales on a slide rule, in particular so that the user could solve multistep problems without having to write down intermediate settings, and with the placement of a legend to make placing the decimal point easier.

The rule slides into an orange leather case lined with chamois. The flap is marked: K + E. Inside the flap is written: PHIL (/) KRUPEN. In 1959, model 4081-5 sold with a leather case for $50.50. Compare to ten-inch versions of model 4081, MA*318482 and MA*334387.

This slide rule was given to the Smithsonian in 1986 by the physicist Philip Krupen (1915–2001). Krupen received his BS from Brooklyn College in 1935, worked on the development of the proximity fuze during and after World War II, earned an MS in physics from The George Washington University, and spent a total of 38 years working for the U.S. government before his retirement in 1973.

This duplex aluminum linear slide rule is coated in yellow ("eye saver") plastic and is held together with stamped aluminum contoured posts. The nylon cursor has a convex lens. The front of the base has +LL1, -LL1, A, D, DI, and K scales, with B, T, ST, S, and C scales on the front of the slide. The left end of the slide is marked: MODEL (/) N-500-ES (/) HI LOG/LOG. The right end of the slide has the Pickett logo used between 1964 and 1975 ("PickETT" with a triangle dotting the i) and MADE IN U.S.A.

There is a black leather case lined with black plastic and marked below the slot for the flap with the Pickett logo in gold. The case has no belt loop. The case fits into a white, green, and black cardboard box. Compare to the box collected with 1995.0126.02. The bottom of this box has a flap marked: PickETT (/) WORLD'S MOST ACCURATE (/) SLIDE RULES. A blue and white sticker on the flap describes the slide rule's features: N500 (/) HI-LOG SPEED RULE (/) THE SUPERIOR TRIG/LOG LOG RULE FOR ESSEN- (/) TIAL ENGINEERING AND TECHNICAL NEEDS (/) All Metal construction for highest accuracy and lifetime (/) performance (/) 22 Key Scales with a comprehensive 60-inch log range (/) With Carrying Case and complete instruction manual (/) Lifetime Guarantee.

The guarantee, with a registration card, is in the bottom of the box, along with the plastic bag that originally contained the slide rule inside the case. The registration card indicates that this example's serial number is A103202 and that the company's headquarters were in Santa Barbara, Calif. The company moved to Santa Barbara in 1964. Along with the logo, this suggests the slide rule was made in the mid-to-late 1960s. Students typically purchased this model in college and continued to use it in their careers.

This aluminum ten-inch linear duplex slide rule is coated in Pickett's "Eye Saver" yellow plastic. The flat nylon indicator is screwed within a white plastic frame. The front top of the base has three extended cube root scales (one for numbers with 1, 4, 7, 10, or more digits before the decimal point; one for numbers with 2, 5, 8, 11, or more digits; and one for numbers with 3, 6, 9, 12, or more digits) and a DF scale. The front bottom of the base has D, DI, and square root scales. The top square root scale gives roots of numbers on the D scale with an odd number of digits before the decimal point; the lower square root scale gives roots of numbers with an even number of digits. The front of the slide has CF, CIF, double T, ST, S, CI, and C scales.

The left end of the slide is marked: MODEL N4-ES (/) Vector-Type LOG LOG (/) DUAL-BASE SPEED RULE. The right end has "Pickett" in script on a triangle with a dot at one point. MADE IN U.S.A. appears beneath the logo. This form of logo was in use from 1958 to 1962. The style of the grooved stamped aluminum posts is also consisted with this timeframe.

The slide rule is in a red-brown leather case lined in white plastic. The triangular Pickett logo is stamped in gold on the front of the case, and a metal ring on the back is for a leather strap (no longer with the instrument) that can be hung around a belt loop. See 1980.0097.04 for instructions.

The donor, engineer Edgar F. Peebles, obtained this slide rule free of charge as a replacement when the numbers came off the slide rule he had used in college. He first used it from 1959 to 1965 in the satellite control facility of the Air Force at Sunnyvale, Calif. He then used it as a down range representative for Lockheed Missiles and Space Company from 1965 to 1968 in tests of the Polaris missile. Finally, from 1968 to 1969 he used the slide rule in the checkout area of the test Polaris missile manufacturing plant in Sunnydale.

Relatively late in its history of making and selling slide rules, the Eugene Dietzgen Co. of Chicago began developing products that competed with the high-end slide rule lines manufactured by Keuffel & Esser (namely, model 4081) and Post (the Versalog). This two-sided, ten-inch wooden slide rule is coated with white plastic and has metal endpieces. On one side the base has LL02, LL03, DF, D, LL3, and LL2 scales, with CF, CIF, L, CI, and C scales on the slide. The top of the base is marked: DIETZGEN MICROGLIDE TM DECIMAL TRIG TYPE LOG LOG CAT. NO. 1734.

On the other side, the base has LL01, K, A, D, DI, and LL1 scales, with B, T < 45°, T > 45°, ST, and S scales on the slide. The top of the base is marked: EUGENE DIETZGEN CO. PATS. 2,170,144 2,285,722 PAT'S PEND. MADE IN U.S.A. 020038. On both sides the right end of the rule has formulas indicating the functions represented by the scales. The glass indicator has a metal and black plastic frame; both edges are marked: DIETZGEN.

The rule fits in a black leather case with a metal clasp. A Dietzgen logo is on the flap—the letter D inside the letter E inside the letters Co. In 1959 Dietzgen introduced the Microglide line of slide rules, which featured Teflon-lined grooves on the base so that the slide moved more smoothly. According to Ian Lodge's estimated production figures, the serial number suggests a manufacture date for this object of 1962.

Dietzgen ceased the production of slide rules around 1972. The arrangement of scales corresponds to those depicted in a 1960 instruction manual for the "Dietzgen Decimal Trig Type Log Log Slide Rule," although the "Microglide" trademark is not mentioned. See 1986.0790.01 for information on the patents mentioned on the instrument. The indicator is Dietzgen's "framed full vision" type and is covered by U.S. Patent 2,634,912, issued to Clarence P. Davey on April 14, 1953.

The donor, Ed Severino, began his career as an engineer with General Electric Company in Schenectady, N.Y. After eight years, he left to teach mathematics and science at Mont [sic] Pleasant High School in Schenectady, where he became head of the Technical Department. The slide rule is of the type trainees used in the late 1970s and early 1980s, when Severino was director of his high school's General Electric Apprentice Training Educational Program.

Numerous slide rule manufacturers also sold rules made by other companies. For instance, the German pencil-manufacturer Staedtler, which used the trade name Mars for slide rules, marketed this ten-inch bamboo rule coated with white plastic and held together with metal L-shaped endpieces. Staedtler's own rules had distinctive light blue slides, but this rule is entirely white. It was made as model 151 between about 1960 and 1972 by the Japanese firm known as San-Ai Measuring Instruments and then as Ricoh Measuring Instruments. Several companies besides Staedtler sold these rules, including Lutz.

On one side, the base has LL/1, LL/2, LL/3, DF, D, LL3, LL2, and LL1 scales, with CF, CIF, CI, and C scales on the slide. The right end of each scale identifies the meaning of the letters, i.e., the C and D scales are marked with an x. The right end of the slide has the company logo of a Greek soldier's head and is marked: STAEDTLER (/) MARS (/) 944 24. On the other side, the base has LL/0, L, K, A, D, DI, P, and LL0 scales, with B, S, ST, T, and C scales on the slide. The indicator is clear plastic with white plastic edges. The bottom edge of the rule is marked: JAPAN.

The rule fits in a brown leather case with a loop for attaching to a belt. The flap is marked: STAEDTLER (/) MARS. The back bottom of the case is marked: JAPAN. A blue and white cardboard box is marked on the end: STAEDTLER MARS (/) 1 BAMBOO SLIDE RULE 944 24 (/) Duplex Log Log 10". See 2009.0019.02.01 for instructions. Compare to 1986.0790.04.

The mathematician and theoretical computer scientist Harley Flanders received this instrument as a gift, but he never used it.

From the late 18th to the mid-19th centuries, British engineers began to use slide rules. This ivory and silver instrument is a four-fold engineer's rule that unfolds to a length of 24 inches. On half of one side is a slide rule with A and D scales on the base and B and C scales on the slide. The A and D scales seem to run continuously, although the slide only moves on the second six inches of the rule.

The words IRON and ROPE appear several times along the edge of the A scale. Along the edge of the D scale is marked: DESCRIPTION SQUARE CYL[I]ND[ER] GLOBE SQUARE CYL[I]ND[ER] WEIGHT STRAIN WORK INCLIN[E] POLYGON SIDE GOVERNORS H[ORSE]P[OWER] ENGIN[E]S STE[A]M TEM[PERATURE]. When the rule is folded, these markings correspond to the tables on the other half of the instrument.

The other half of this side has a table of gauge points for the A scale. Instructions printed on the rule suggest that calculations on the slide rule were intended to be made with calipers. Additional tables and instructions for working with ropes and chains are on this half, which is marked: IMPROVED & ARRANG[E]D (/) BY RT HAWTHORN (/) CIVIL ENGINEER (/) NEWCASTLE TYNE.

The other side has a scale of 24 inches divided to eighths of an inch along the edge. The metal joint has a protractor divided in increments of 5 degrees and marked by tens from 0 to 180. When the instrument is folded around the joint, there are tables for the extreme strain possible in bars and beams of various substances and for equivalent measures. The joint is marked: G. R. STEPHENSON (/) ENGINEER (/) Adam Pensom.

In 1832 civil engineer Robert Hawthorn (1796–1867) designed a new form of slide rule for manufacturing locomotives and other engines. In 1859 dealers sold the rule for 5 shillings and 6 pence. The names on the joint may refer to the British civil engineer George Robert Stephenson (1819–1905), nephew to the engineer George Stephenson (1781–1848), who sought mechanical advice from Hawthorn's father, and to Adam Pensom (b. 1824), who was a retired gas engineer living in London, according to the 1881 British census. The Smithsonian acquired this object in 1973.